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Themed #seabirdersaturday: Egg colour and photography

Nina O'Hanlon, July 21, 2015
 

Hi, this Saturday, 25 July, from 1300-1500 GMT (2300-0100 AEST, 1400-1600 BST, 0900-1100 ET, 0600-0800 PT) I will be hosting the themed #seabirdersaturday on Twitter on using digital photography to measure egg colour.

Eggshell colouration can vary dramatically within and between bird species in terms of both background colour and maculation, or patterning. This has led to much research and several hypotheses being put forward to explain this variation including crypsis, structural strength, adaptation to brood parasitism, protection from solar radiation and signalling female quality or condition.

If egg colour can reflect information about female condition, and therefore about the local environment, then this could provide a relatively simple and cost-effective monitoring tool - especially if the information can be obtained quickly in the field using digital photography.

Unfortunately, it is not as straightforward as simply taking a photograph. I am no expert in this area, however, I will be tweeting about our experience of using digital photography to quantify the colour of herring gull eggs and the issues we came across. I will also cover some of the background of eggshell colouration, the pigments involved, uses of egg colour in other studies and any questions you might have.

So far questions I will cover include: • How we standardised taking photographs of eggs in the field • Setting the camera to account for taking photographs in different light conditions • How to extract colour information from digital photographs • How we dealt with non-linearity in the cameras response to light intensity • What other information can be extracted from egg photographs

Nina O’Hanlon

PhD Student, University of Glasgow

Comments ( 4 )

Lex van Groningen

Lex van Groningen

Hello Nina, I am not a bird researcher, but a photographer who is passionate about albatrosses and other tubenosed birds. I have also had to deal with colour accuracy & consistency photographing works of art (paintings) lately. When [1] photographing bird's eggs, lighting conditions will always be different. The clue is to use a reference colour (set). A (standardised) photograic grey card should be photographed along with the egg, so the grey can be used to later on set the white balance. I use an alternative device called the Spyder Cube, but it does the same thing. Take this one step further and you will be using a colour board, with reference colours. The grey card or colour board will [2] then be used in the computer to set the correct white balance. However, this also requires the computer screen to be calibrated, otherwise all work is in vain. Last but not least: while photographing the eggs with a reference colour alongside, why not adding a ruler to capture (basic) information about the egg size?

If you want more information you can contact me via lex@lexsample.nl.

Good luck!

Nina O'Hanlon

Nina O'Hanlon

Hi Lex, Thanks very much for you comment. Luckily we did use a reference colour strip when taking photographs so it is good to know this option has worked elsewhere. It was quite time consuming correcting the values though so I like the idea of a colour board that the computer can automatically adjust for!

Lex van Groningen

Lex van Groningen

Hello Nina,

Check for example: https://www.youtube.com/watch?v=4-XGpIVGxTA to find out how this works (using the colour chart and then adjusting the pictures in the computer). For field work (more harsh and wet condition than studio photography!) I would advise to look into a cheaper and maybe more slim/portable version of the Spyder colour chart used in the video. But it's more the idea that I mean, not so much the product (it's just as an example). Good luck..!